Serial-type inkjet recording apparatuses produce a complete image on a recording medium, such as a sheet of paper, by repeating an operation of causing a recording head having nozzle arrays for ink ejection to scan the recording medium in a scanning direction and an operation of conveying the recording medium in a conveying direction orthogonal to the scanning direction. In such inkjet recording apparatuses, a recording head having a so-called horizontal structure is known in which nozzle arrays for inks of multiple colors (e.g., cyan, magenta, yellow, and black) are arranged in the scanning direction. In inkjet recording apparatuses using a recording head having a horizontal structure, a difference in ink recording sequence (typing sequence) between forward and backward scanning directions causes variations in color (hue or saturation) from one band to another, which results in color non-uniformity and leads to a degradation in image quality.
Patent Literature 1 (PTL 1) discloses a technique which involves dividing a band in a scanning direction into multiple regions, for each of which a determination is made such that the higher the recording duty, the larger the number of passes for multipass recording.